A circular monopole antenna with modified partial ground plane for ultra wideband (UWB) applications is investigated in this paper. The proposed antenna is fed by a 50 Ω tapered microstrip line, and printed on a FR4 substrate with relative permittivity of 4.3 and height of 1.6 mm. All optimal parameters have been achieved to accomplish S<inf>11</inf> better than -10 dB with a nearly omnidirectional pattern and maximum gain of 3.83 dBi over 3.1-10.6 GHz. In addition, antenna prototype was fabricated and conducted experiment to verify the simulation. Apparently, simulated results are in very good agreement with the experimental results.
